Who is Baroness Theresa de Stolberg from Wieland; and Memoirs of Carwin the Biloquist and what is their importance?

Baroness Theresa de Stolberg is Pleyel's lover. She later becomes his wife. Theresa faked her own death in order to join Pleyel in America, but her scheme misfired when the news of her death reached Pleyel, causing him great pain. In the end, Pleyel married her more out of a sense of honor and duty than out of love. After her death, Pleyel reconciled with Clara.